We do not recommend humidifiers that produce visible moisture.

I previously reported that 7 to 8 percent of Japanese adults, both housing professionals and the general public, believe that "clouds are water vapor." This was confirmed by a show of hands from over 1000 people, so I think it's pretty accurate. Clouds are actually small particles of either water or ice suspended in the air. However, most people believe that the white mist is water vapor.

In middle school or high school, we learn that there are three states of matter: solid, liquid, and gas. In the case of water, these are ice, water, and water vapor. Gas is usually invisible. Therefore, if it is visible, it is definitely not water vapor.

So what exactly is the name for that thing you see in your bathroom or above your humidifier?

I think it would not be wrong to use the general term "steam" to describe what you see above the bathtub. However, not everything you see above a humidifier is steam. Although their use has become much less common in recent years, there is a type of humidifier known as the steam type. This uses an electric heating wire to heat water and vaporize it, so it works on the same principle as a bathtub. The result is the same, and steam appears. Generally speaking, steam refers to the phenomenon in which warm water vaporizes in a relatively low temperature location and quickly turns back into small droplets of water (liquefies), becoming visible.

In contrast, humidifiers like those sold at general stores, and plastic bottle-type humidifiers, are almost always ultrasonic. This method involves applying ultrasound (i.e. micro-vibrations) to water to break it into small droplets at room temperature and spraying them into the air. A device that manually breaks water into small droplets is called a "mist bottle," but this is a device that uses mechanical power to break down water into small droplets. I don't think anyone would agree with calling the small droplets of water created in this way "steam." If you were forced to call it something, I think the only thing you could call it is "mist."

In the case of steam and evaporative types, not only the chlorine in the water, but also mold and bacteria remain inside the main unit and are not dispersed into the air. As a result, chlorine may precipitate inside the main unit if used for a long time. On the other hand, ultrasonic types have the tendency to disperse all of these things into the air regardless of the circumstances. If the inside is kept clean, it will not scatter mold or bacteria, but if it is dirty, it is not good. Even if it is clean, it will definitely scatter chlorine. As a result, home appliances, especially chlorine, can become completely white due to static electricity.

Diseases caused by ultrasonic humidifiers like this are commonly referred to as "humidifier disease," and even a quick search will bring up a large number of results.

For these reasons, I do not recommend ultrasonic cleaners. I have tried using one once, but the instructions say to place it at a height of 50cm or higher. The reason is obvious when you use it, as small droplets of water are much heavier than air, so especially when the room temperature is low, they will not evaporate and will fall to the ground as water. The floor will become sticky. The higher the height, the higher the chance of evaporation before it falls, so this is probably why the instructions say so.

Steam type humidifiers require a lot of heat and therefore consume a lot of electricity. Also, like the evaporative type we explained the other day, they continue to humidify the air even if it is already humid, so cloths and sheets may become damp.

The phenomenon of evaporation is easier when the surface area is increased. The easiest example to understand is a clothesline. If it is folded, it takes a long time to dry, but if you spread it out, it dries quickly. When water is stored in a container, there is only a very small surface area that comes into contact with the air. When it breaks down into small particles like mist, the surface area becomes larger and it evaporates more easily even without the need for heat. Therefore, as mentioned above, water that does not evaporate and falls directly to the floor does not humidify the air.

The table below shows a schematic diagram of how the surface area increases when the particles are made smaller. You can see that the surface area doubles just by dividing the particle into eight parts.

I have the opportunity to visit the offices of various companies. I think that it is better to have a humidifier, regardless of the type, than not having one at all. However, even if they do have one, most of them are ultrasonic. The amount of humidification is small to begin with, and the fan power is also weak, so there is a high possibility that only the very surrounding area is humidified.

We only recommend large evaporative humidifiers, which produce a considerable amount of airflow. However, since nothing visible comes out, most people don't really feel like they're humidifying the air.